Investigation of choice in vestibular schwannoma -

Ans. is 'a' i.e., MRI Investigations of acoustic neuroma1) Audiovestibular testso Audiological tests show retrocochlear type of SNHLi) SNHL is more marked in high frequencies on pure tone audiometryRecruitment absentTone decay is significantSISI score 0-20%Speech discrimation is highly impaired on speech audiometry and this is disproportionate to hearing loss. Roll over phenomenon is present, i.e. reduction in discrimnation score when loudness is increased beyond a particular limit.o Acoustic reflex show stapedial reflex decay.o Caloric test (vestibular test) :- Diminished or absent response but may be normal if tumor is very small.2) Radiological testso Gadolinium enhanced MRI is the most sensitive and specific test to demonstrate acoustic neuroma. Even small intracanalar (intrameatal) tumor can be detected.o CTscan does not generally identify- small intracanalicular (intrameatal) tumors. CT scan is used for CP angle exploration, but intracanalicular acoustic neuroma go unnoticed, even with contrast medium,o Vertebral angiography is helpful to differentiate acoustic neuroma from other tumors of cerebellopontine angle when doubt exists.